Why is this bone not keyfaming or animating when keyframed?
As the error message hints, your animation channels are locked:



You need to click the padlock icon next to the bone name in the Dopesheet Editor to unlock them all. You probably just clicked it by accident. This solves being able to insert new keyframes, but the bone still doesn't move when animated. This is because the location channels are also muted:



Locking protects the animation channels from being edited (inserting/deleting keyframes) and muting temporarily disables them (hides their effects).